1. Field of the Invention
The pyrazoloxanthene compounds represented by general formula I are novel compounds which are useful as color formers in pressure or heat sensitive imaging papers. As prepared by the process of this invention these compounds are colorless, or only lightly colored. Upon contact with an acidic electron-acceptor material, the compounds of this invention are converted to resonance forms which are highly colored. This conversion to resonance form takes place as follows: ##SPC1##
2. Description of the Prior Art
The prior art shows a number of chemical compounds which are stated to be useful as color formers. While these have the common property of converting from essentially colorless to highly colored resonance forms of contact with acidic electron acceptor materials, none of the prior art compounds includes a fused heterocyclic pyazolo ring on a xanthene structure.